1. Field of the Disclosure
Embodiments disclosed herein relate generally to systems and methods of mixing fluids used in oilfield applications. More specifically, embodiments disclosed herein relate to systems and methods for mixing wellbore fluids and fluids used for production enhancement using a modular system. More specifically still, embodiments disclosed herein relate to system and methods for mixing, storing, and injecting fluids during varied operations at drilling and production location.
2. Background Art
When drilling or completing wells in earth formations, various fluids typically are used in the well for a variety of reasons. Common uses for well fluids include: lubrication and cooling of drill bit cutting surfaces while drilling generally or drilling-in (i.e., drilling in a targeted petroliferous formation), transportation of “cuttings” (pieces of formation dislodged by the cutting action of the teeth on a drill bit) to the surface, controlling formation fluid pressure to prevent blowouts, maintaining well stability, suspending solids in the well, minimizing fluid loss into and stabilizing the formation through which the well is being drilled, fracturing the formation in the vicinity of the well, displacing the fluid within the well with another fluid, cleaning the well, testing the well, transmitting hydraulic horsepower to the drill bit, fluid used for emplacing a packer, abandoning the well or preparing the well for abandonment, and otherwise treating the well or the formation.
In general, wellbore fluids should be pumpable under pressure down through strings of drilling pipe, then through and around the drilling bit head deep in the earth, and then returned back to the earth surface through an annulus between the outside of the drill stem and the hole wall or casing. Beyond providing drilling lubrication and efficiency, and retarding wear, drilling fluids should suspend and transport solid particles to the surface for screening out and disposal. In addition, the fluids should be capable of suspending additive weighting agents (to increase specific gravity of the mud), generally finely ground barites (barium sulfate ore), and transport clay and other substances capable of adhering to and coating the borehole surface.
While the preparation of wellbore fluids may have a direct effect upon their performance in a well, as well as the production of the well, methods of fluid preparation have changed little over the past several years. Typically, the mixing method still employs manual labor to empty sacks of fluid components into a hopper to make an initial fluid composition. However, because of agglomerates formed as a result of inadequate high shear mixing during the initial production of the fluid composition, screen shakers used in a recycling process to remove drill cuttings from a fluid for recirculation into the well also filter out as much as thirty percent of the initial fluid components prior to the fluid's reuse. In addition to the cost inefficiency when a drilling fluid is inadequately mixed, and thus components are aggregated and filtered from the fluid, the fluids also tend to fail in some respect in their performance downhole. Inadequate performance may result from the observations that the currently available mixing techniques hinder the ability to reach the fluids rheological capabilities. For example, it is frequently observed that drilling fluids only reach their absolute yield points after downhole circulation. The mixing of production fluids including, for example, produced water and polymers, may also include the manual mixing of dry components in a hopper, then adding the dry components to a liquid. Similar to the mixing of drilling fluids, improper mixing of production fluids may result in fluids that fail to enhance the recovery of hydrocarbons from formation when pumped downhole.
Furthermore, for wellbore fluids that incorporate a polymer that is supplied in a dry form, the adequacy of the initial mixing is further compounded by the hydration of those polymers. When polymer particles are mixed with a liquid such as water, the outer portion of the polymer particles wet instantaneously on contact with the liquid, while the center remains unwetted. Also effecting the hydration is a viscous shell that is formed by the outer wetted portion of the polymer, further restricting the wetting of the inner portion of the polymer. These partially wetted or unwetted particles are known in the art as “fisheyes.” While fisheyes can be processed with mechanical mixers to a certain extent to form a homogenously wetted mixture, the mechanical mixing not only requires energy, but also degrades the molecular bonds of the polymer and reduces the efficacy of the polymer. Thus, while many research efforts in the fluid technology area focus on modifying fluid formulations to obtain and optimize rheological properties and performance characteristics, the full performance capabilities of many of these fluid are not always met due to inadequate mixing techniques or molecular degradation due to mechanical mixing.
Accordingly, there exists a need for improved techniques for mixing wellbore fluids.